1. Field of the Invention
The present invention relates to a colored contact lens designed to be used as a trial lens.
2. Related Art
The use of contact lenses to improve the optical properties of the eye and for reasons of appearance in continuously becoming more popular. One of the obstacles to more widespread use is the great diversity of the properties of human eyes, i.e. the fact that some people can directly start wearing contact lenses and others need a long break-in period while some people""s eyes never become adapted to contact lenses. For this reason, before making an actual buying decision or before buying e.g. a batch of dozens of disposable lenses, a person needs to have a chance to try the lenses to see whether his/her eyes get adapted to them.
To lower the threshold to the use or at least trial of contact lenses, manufacturers of contact lenses have introduced the practice of delivering trial lenses or test lenses free of charge to allow the user to establish whether his/her eyes will adapt to wearing contact lenses. Since the eye is a very delicate organ and sensitive to any foreign elements and also very susceptible to injury, trial lenses have to be manufactured with absolute precision and in a manner fully corresponding to actual contact lenses. Therefore, contact lenses must be completely equivalent to actual contact lenses in respect of all their properties.
To ensure that people will not make illegal use of trial lenses by getting new trial lenses again and again from different dealers, manufacturers have provided trial lenses with a marking text like xe2x80x98testxe2x80x99, xe2x80x98trialxe2x80x99 or xe2x80x98demoxe2x80x99, printed either in the limbal part or on the iris ring. In spite of this, trade in free trial lenses has become a significant business, in other words, there are persons who visit different contact lens dealers to get free trial lenses, which they then sell on suitable markets for a good price.
The object of the invention is to eliminate the above-mentioned drawbacks. A specific object of the invention is to disclose a colored contact lens that is completely equivalent to actual contact lenses in respect of its optical properties but that is visually sufficiently different from actual contact lenses to ensure that it can only be used for a short time as a trial lens.
The colored contact lens used as a trial lens consists of a circular plastic lens having a convex outer surface and comprising a clear limbal ring at the outer edge of the lens and a clear pupillary part in the middle of the lens. In addition, the lens has between the limbal ring and the pupillary part an iris ring provided with a continuous pattern produced with a coloring agent. The continuous pattern may consist of a substantially uniform colored surface, repeated texture, continuous coherent form or continuous random texture surface. According to the invention, the iris ring comprises a visually perceptible discontinuity area that breaks the continuous pattern. In other words, according to the invention, the iris ring has a distinct, visible area that differs from the continuous pattern, a shape of colored surface that gives the contact lens an appearance producing a definitely unsatisfactory impression.
The discontinuity area comprises a proportion of 5-90%, possibly 10-30%, e.g. 12-20% of the total area of the iris ring.
The discontinuity area is preferably a clear area without coloring agent, in other words, it is produced by leaving a given area of the iris ring free of coloring agent when the contact lens is being colored. Another possibility is to give the discontinuity area a color that differs from the pattern, in other words, the discontinuity area is tinted with a color differing from the main iris ring color. In this case, the color used preferably differs an much as possible from the color of the iris ring.
In general, the iris ring pattern and coloring of a colored contact lens are designed to imitate the pattern of the iris ring of a real eye, i.e. its random radial stripe pattern with varying width of and spaces between the stripes. However, it is possible that the coloring agent used in the iris ring of the trial lens forms a substantially uniform dye layer on the colored surface of the iris ring, the coloring agent forms a substantially cyclically varying pattern on the colored surface of the iris ring or the coloring agent forms distinct sharp shapes or patterns on the colored surface of the iris ring.
The invention does not define the shape of the discontinuity area to be used in the iris ring in any way; instead, the discontinuity area may have the shape of e.g. a sector, a segment, a strip of substantially even width going through the iris ring of the lens, an area of determined or undetermined shape, or it may consist of several separate sub-areas of varying shape without coloring agent or provided with a differing coloring agent.
The colored contact lens of the invention has many significant advantages as compared with prior art. In respect of its optical properties, the contact lens of the invention is completely equivalent to a normal colored contact lens. The fit of the lens and the eye response produced by it fully correspond to a normal contact lens. Yet it looks so anomalous, abnormal and defective that hardly anyone would like to wear such lenses longer than necessary for trial, and consequently nobody is willing to pay anything for them. Thus, as demand fades, there will be an end to the practice of collecting and selling free trial lenses. Besides, if the discontinuity area is clear and untinted, the user can easily compare his/her own iris visible through it with the colored iris ring and thus clearly see the color change of his/her eye before making a final purchase decision.